anyone click the link download starts and will take time to finish
depending on the size of the file.

>
> 3.Now i want to track from server side script or any other means

that how much bytes is transferred.

>
>
> after one successful download i have to remove the link from my

site .... removing the link is pretty easy but the problem is how can
i know that this file is successfully downloaded to the pc once.

> Can i track how many bytes is downloaded from server?

---> It is possible as far i can think, i will dicuess this issue in
later question...

> his/her download might be interrupted by a disconnection, then it

would not be a successfull download.

> after one 100% download i have to set a flag=1 to remove the link

dynamically.

> Is there any means to identify such a 100% successful download.
>

---> Some way it should be possible like if you handle your download
using PHP Script... where your PHP script open requested file and
transfer bit by bit... and your script updates a static counter in
your shared memory or any physical file...

Client end responsive UI will fetch that counter value after reloading
contents... (it might be using Ajax)

** How to ensure successful download:
If you handle your download using your own script... you know when a
download should be successful...
here is some logic...